Pinch detection device and opening/closing device

ABSTRACT

A pinching detection apparatus having a pressure sensor  2  disposed along the geometry of a trunk lid  1  in a flexible manner, and determination means  16  for detecting that an object is being pinched between a body opening section  7  and the trunk lid  1 , in accordance with a signal output from the pressure sensor  2 . Since the pressure sensor  2  is disposed along the geometry of the trunk lid  1  in a flexible manner, pinching by the trunk lid  1  can be detected.

FIELD OF THE INVENTION

The present invention relates to a pinching detection apparatus whichdetects that an object is being pinched between a body opening sectionof a vehicle, such as an automobile, and a trunk lid, as well as to anopening/closing apparatus.

BACKGROUND TECHNIQUE

A related-art pinching detection apparatus has a motor-driven trunk lidand indirectly detects that an object is being pinched between a bodyopening section and the trunk lid, on the basis of a change in thedriven state of the motor which arises when the object has been pinchedbetween the body opening section and the trunk lid (see, e.g.,“Introduction of State-of-the-Art Embedded in E65, No. 1, Exterior,” May7^(th), 2002, http://www.bohp.net/html/event91.htm).].”

However, according to the above-described related-art configuration,occurrence of pinching is detected on the basis of a change in a drivenstate of a motor; e.g., a change in a drive current supplied to themotor. For this reason, there is no alternative but to increase athreshold for detecting pinching so as to prevent occurrence oferroneous detection of pinching, which would otherwise be caused by anincrease in drive resistance, such as squeaking of a drive mechanismattributable to age-related deterioration, or the like.

Therefore, when an object is actually being pinched, the load exerted onthe object becomes larger, thereby raising a problem of increasing thechance of inflicting damage on the pinched object.

Moreover, during closing operation of the trunk lid, greater rotationaltorque acts on an area close to a rotary shaft of the trunk lid ascompared with the rearmost portion of the trunk lid. Hence, there arisesa problem of greater damage being inflicted on an object when the objectis caught between the body opening section and the trunk lid close tothe rotary shaft of the trunk lid than when the object is caught at therearmost portion of the trunk lid.

DISCLOSURE OF THE INVENTION

In order to solve the problem, the present invention is provided with apressure sensor disposed along an outer edge of a trunk lid of avehicle, and determination means for detecting an object being pinchedbetween a body opening section of the automobile and the trunk lid, onthe basis of a signal output from the pressure sensor. Pinching causedby the trunk lid can be detected by means of the pressure sensor.

To solve the problem, the present invention enables detection ofpinching caused by the trunk lid, by means of the pressure sensordisposed along the outer edge of the trunk lid.

The pressure sensor has a flexible piezoelectric sensor. Under asituation where a contact-type pressure-sensitive switch comprising aplurality of mutually-opposing electrodes is used as the pressure sensorand disposed along the trunk lid, if the trunk lid has a bent section,the electrodes contact each other at that bent section, thereby causingerroneous detection. In contrast, the piezoelectric sensor has nocontacts. Even when the piezoelectric sensor is disposed along bentareas, the sensor can detect occurrence of pinching without involvementof occurrence of a detection error, whereby enhanced reliability isachieved.

The pressure sensor has a nonlinear flexible member whose displacementin response to load is nonlinear. The piezoelectric sensor is disposedadjacent to the nonlinear flexible member. For instance, even when anobject is pinched when the closing speed of the trunk lid is slow, thenonlinear flexible member is quickly deformed as a result of thepressing load exerted on the pressure sensor by the object havingreached a predetermined value or more, and the adjacently-disposedpiezoelectric sensors also undergo sudden deformation, therebyoutputting a large output signal. As a result, occurrence of pinchingcan be determined by the determination means, and reliability concerningdetection of pinch is greatly enhanced.

The determination means determines whether or not the object maintainscontact with the object, on the basis of the signal output from thepiezoelectric sensor. For instance, when the object is determined tomaintain contact with the piezoelectric sensor, control for inhibitingclosing of the trunk lid becomes feasible, thereby resulting in enhancedreliability.

The pressure sensor has a cushioning section which can be compressed bythe pressure stemming from the pinched object. Even when occurrence ofpinching has been detected, the cushioning section is compressed untilmovement of the trunk lid is reversely moved. Therefore, an increase inpinching load applied to the object can be prevented, to thus diminishstress or damage inflicted on the pinched object.

Moreover, the present invention further comprises the above-describedpinching detection apparatus, drive means for driving the trunk lid, andcontrol means for controlling the drive means so as to release pinchingwhen pinching is determined to have arisen on the basis of the signaloutput from the determination means. Pinching is released when pinchingis determined to have arisen, and hence occurrence of unwanted pinchingcan be prevented.

When the trunk lid is closed, the drive means is controlled such thatthe trunk lid is closed after the trunk lid has once been moved over apredetermined distance in an opening direction. Even when the object hascome into contact with the piezoelectric sensor before the trunk lidstarts closing, the trunk lid is closed after having once been movedover a predetermined distance in an opening direction. The inertialforce of the object having moved in the opening direction is applied tothe piezoelectric sensor by means of the closing action, therebyreliably pressing the piezoelectric sensor. Therefore, occurrence ofpinching can be reliably detected.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1(a) is an external view of a pinching detection apparatus and anopening/closing apparatus, both belonging to a vehicle, according to aninvention of a first embodiment when the pieces of the apparatus areviewed in the lateral direction of the vehicle;

FIG. 1(b) is an external view of the apparatus when viewed from the rearof the vehicle;

FIG. 2(a) is an external view of a case where a pressure sensor isprovided on either side of the trunk lid;

FIG. 2(b) is an external view of a case where a single pressure sensoris disposed along both sides and a lower edge of the trunk lid;

FIG. 3(a) is a cross-sectional block diagram taken along line A-A inFIG. 1 when the trunk lid is closed;

FIG. 3(b) is a cross-sectional block diagram taken along line A-A shownin FIG. 1(a) while an object is pinched between the trunk lid and anopening section of the body;

FIG. 4 is an external view of a pressure sensor of the apparatus;

FIG. 5 is a block diagram of the apparatus;

FIG. 6 is a characteristic plot showing a signal V output from afiltering section of the apparatus, a determination output produced by apinch determination section, and a voltage Vm applied to a motor;

FIG. 7(a) is a cross-sectional profile of a pinching detection apparatusand a pressure sensor of an opening/closing apparatus, both pertainingto an invention of a second embodiment (showing that no load is appliedto the pressure sensor);

FIG. 7(b) is a cross-sectional profile of the pinching detectionapparatus and the pressure sensor of the opening/closing apparatus, bothpertaining to the invention of the second embodiment (showing that apredetermined load or more is applied to the pressure sensor, and thepressure sensor is compressed);

FIG. 8 is a characteristic plot showing a signal V output from afiltering section of a pinching detection apparatus and anopening/closing apparatus, both pertaining to an invention of a thirdembodiment, and a determination J output from a pinch determinationsection of the same apparatus; and

FIG. 9 is a characteristic view showing a voltage Vm applied to a drivemeans belonging to a pinching detection apparatus and an opening/closingapparatus according to an invention of a fourth embodiment.

BEST MODES FOR IMPLEMENTING THE INVENTION

Embodiments of the present invention will be hereinbelow described byreference to FIGS. 1 to 9.

First Embodiment

An invention of a first embodiment will be described by reference toFIGS. 1(a) to 6.

FIG. 1(a) is an external view of a pinching detection apparatus and anopening/closing apparatus of the invention of the first embodiment asviewed from a lateral direction of a vehicle body (showing a state wherea trunk lid is open), and FIG. 1(b) is an external view of the same asviewed from the rear of the vehicle body (showing a state where thetrunk lid is closed), both views showing a configuration where apressure sensor 2 is disposed on a trunk lid 1 of a vehicle is shown.FIG. 2 is external views showing a placement location of the pressuresensor 2 on the trunk lid 1, where the trunk lid 1 is viewed from theinterior of the vehicle. FIG. 2(a) shows a state where the pressuresensor 2 is disposed on each of right and left sides of the trunk lid 1,and FIG. 2(b) shows a state where a single pressure sensor 2 is disposedalong both the right and left sides and a lower end of the trunk lid 1.

FIGS. 3(a) and 3(b) are cross-sectional views showing the configurationas viewed along line A-A of FIGS. 1. The upper side of the drawingsindicates an inside of a vehicle compartment; and the lower sideindicates an outside of the vehicle. FIG. 3(a) shows a state where thetrunk lid 1 is closed and the pressure sensor 2 is disposed at an endsection 3 of the trunk lid 1 by way of support means 4. Referencenumeral 5 denotes a vehicle body; and reference numeral 6 denotes a sealsection which seals a gap between a body opening 7 and a body 5, and thetrunk lid 1 when the trunk lid 1 is closed. The pressure sensor 2 isfixed to the end section 3 with a clearance of a predetermined distancefrom the body 5 so as not to come into contact with the body 5 when thetrunk lid 1 is completely closed. In consideration of the possibility ofpinching of a finger of a child or the like, this distance is preferablyset to 3 to 5 mm. FIG. 3(b) is a cross-sectional view showing theconfiguration as viewed along the line A-A of FIGS. 1, showing a statewhere an object Q is pinched between the trunk lid 1 and the bodyopening 7.

FIG. 4 is a view showing the configuration of the pressure sensor 2. Asshown in FIG. 4, the pressure sensor 2 is configured such that aflexible, piezoelectric sensor 9 is disposed in an elastic member 8. Thepiezoelectric sensor 9 has a coaxial cable-like configuration which isformed by means of concentrically stacking a composite piezoelectriclayer 10 serving as a piezoelectric material, and a center electrode 11and an external electrode 12 serving as electrodes which sandwich thecomposite piezoelectric layer 10, whereby the pressure sensor 2 isconfigured so as to have excellent flexibility as a whole. Thepiezoelectric sensor 9 is manufactured through the following process.First, a chlorinated polyethylene sheet and piezoelectric ceramic powder(in the embodiment, lead titanic acid zirconate) in an amount of 40 to70 vol % (volume%) are uniformly mixed into a sheet by means of arolling method. The sheet is cut into fine pellets, and these pelletsare continuously extruded in conjunction with the center electrode 11,thereby forming the composite piezoelectric layer 10. The externalelectrode 12 is wound around the composite piezoelectric layer 10. Theelastic member 8 surrounding the external electrode 12 is also extrudedcontinuously. Finally, for the purpose of polarizing the compositepiezoelectric layer 10, high, direct-current voltage of 5 to 10 kV/mm isapplied between the center electrode 11 and the external electrode 12.

Prior to addition of the piezoelectric ceramic powder to the chlorinatedpolyethylene, the piezoelectric ceramic powder is preferably immersed ina solution of titanium coupling agent, and dried. Through thistreatment, the surface of the piezoelectric ceramic powder is coveredwith a hydrophilic group and a hydrophobic group, which are contained inthe titanium coupling agent. The hydrophilic group prevents aggregationof the piezoelectric ceramic powder; and the hydrophobic group increaseswettability between the chlorinated polyethylene and the piezoelectricceramic powder. As a result, the piezoelectric ceramic powder can beuniformly added in the chlorinated polyethylene with a high content ofup to 70 vol %. It is found that the same effect as above can beobtained when the titanium coupling agent is added during the course ofrolling of the chlorinated polyethylene and the piezoelectric ceramicpowder in place of immersion in the titanium coupling agent solution.This treatment is excellent in that no particular immersion treatment ina titanium coupling agent solution is required.

An ordinary metal single lead wire may be employed as the centerelectrode 11; however, in the embodiment, such an electrode that a metalcoil 14 is wound around an insulating polymer fiber 13 is employed. Asthe insulating polymer fiber 13 and the metal coil 14, a polyester fiberand a copper alloy containing 5 wt % of silver are preferably employed.

The external electrode 12 is configured such that a strip electrode,constructed by means of affixing a metal film to a polymer layer, iswound around the composite piezoelectric layer 10. An electrode, whichuses polyethylene terephthalate (PET) as the polymer layer, and on whichan aluminum film is affixed, is preferable as the external electrode 12,because such an electrode has high thermal stability at 120° C. and iscommercially mass-produced. Meanwhile, for the purpose of shielding thepiezoelectric sensor 9 from electrical noise of the externalenvironment, the external electrode 12 is preferably wound around thecomposite piezoelectric layer 10 in such a manner as to partiallyoverlap itself

An elastic material, such as rubber, of higher flexibility andelasticity than the piezoelectric sensor 9 is employed as the elasticmember 8 so that the piezoelectric sensor 9 easily deforms underpressure applied as a result of pinching of an object in considerationof heat resistance and cold resistance in view of an in-vehiclecomponent; specifically, a material which exhibits a small degree ofdegradation in flexibility at −30 to 85° C. is preferably selected. Forinstance, ethylene propylene rubber (EPDM), chloroprene rubber (CR),butyl rubber (IIR), silicone rubber (Si), or a thermoplastic elastomermay be used as such rubber. In addition, the elastic member 8 has acushioning section 15 which is formed so as to have a hollow space andwhich can be compressed under pressure applied by a pinched object.Furthermore, a groove for enabling fixed support by the support means 4is formed in the bottom of the elastic member 8.

When the pressure sensor 2 is attached to the trunk lid 1, first, thesupport means 4 is formed so as to allow attachment along the endsection of the trunk lid 1; and the pressure sensor 2 is fixed to thethus-formed support means 4. Subsequently, a sensor member constitutedof the pressure sensor 2 and the support means 4 is attached to the endsection of the trunk lid 1. As a method of fixing, for instance,fastening to a fixation hole formed on the support means 4 by means of ascrew may be employed.

In a case where a contact-type pressure switch constituted of aplurality of opposing electrodes is employed as the pressure sensor 2and disposed on the trunk lid 1, when the trunk lid 1 includes a bentsection, the electrodes are brought into contact with each other at thebent section, and cause erroneous detection. However, since thepiezoelectric sensor 8 has no contact, even when the sensor 8 isdisposed at a bent section, an erroneous detection does not occur.Therefore, in the first embodiment, by virtue of the above-mentionedconfiguration, even when the trunk lid 1 includes a bent section R asshown in FIGS. 2, the pressure sensor 2 can be disposed along the bentsection R.

FIG. 5 is a block diagram of the pinching detection apparatus and theopening/closing apparatus of the invention of the first embodiment. Asshown in FIG. 5, reference numeral 16 denotes determination means; 17denotes a circuit-side resistor for detecting disconnection; 18 denotesa signal lead-through resistor for leading signals output from thepiezoelectric sensor 8; 19 denotes a filter section which allows passageof only predetermined frequency components of an output signal from thepiezoelectric sensor 8; 20 denotes a determination section fordetermining occurrence of pinching on the basis of the output signalfrom the filter section 19; 21 denotes an anomalous conditiondetermination section for determining an anomaly such as malfunction ofthe piezoelectric sensor 8; 22 denotes a connector; 23 denotes abattery; 24 denotes drive means for driving the trunk lid 1; 25 denotescontrol means for controlling the drive means 24 on the basis of anoutput signal from the determination means 16; and 26 denotes a displaysection for displaying, on a front panel in a vehicle compartment or thelike, a result of determination by the determination means 16. Forinstance, an electric motor is employed as the drive means 24. Referencenumeral 27 denotes a sensor-side resistor which is disposed, as aresistor for detecting disconnection, between the center electrode 10and the external electrode 11 at an end section of the piezoelectricsensor 8.

The filter section 19 has such filtering characteristics as to rejectunwanted signals derived from vibrations of a vehicle body, and thelike, from the output signal of the piezoelectric sensor 8, to thusextract signals having frequency components which are characteristic topinching of an object. The filtering characteristic may be determined soas to be optimized in consideration of vibration characteristics of thevehicle body, and the like. More specifically, for the purpose ofeliminating vibrations generated by a vehicle engine and running, thefilter section is preferably embodied as a low pass filter whichextracts signal components of about 10 Hz or lower.

The piezoelectric sensor 8 and the determination means 16 are directlyconnected; and the determination means 16 is disposed on an upper end ofthe trunk lid 1, or incorporated in the same. For the purpose ofeliminating external electrical noise, the entire determination means 16is preferably covered by a shielding member and electrically shielded.Alternatively, a lead-through capacitor or an EMI filter may be added toan input/output section of the determination means 16 as acountermeasure against a strong electric field.

Next, operations will be described. As shown in FIG. 3(b), when theobject Q is pinched between the trunk lid 1 and the body opening 7, theobject Q is brought into contact with the pressure sensor 2. Pressureapplied from the object Q deforms the piezoelectric sensor 8 in thepressure sensor 2.

FIG. 6 is a characteristic diagram for this case showing an outputsignal V of the filter section 19, a determination output J of the pinchdetermination section 20, and an applied voltage Vm applied to the drivemeans 24. In FIG. 6, V, J, and Vm are plotted on the Y axis, in thisorder from the top; and time “t” is plotted on the X axis. At time t1, avoltage of +Vd is applied, to thus drive the trunk lid 1 in a closingdirection. When pinching occurs, the piezoelectric sensor 8 outputs asignal (a signal component larger than a reference voltage V0 in V ofFIG. 6) in accordance with an acceleration of deformation of thepiezoelectric sensor 8 by the piezoelectric effect. When V-V0, which isan amplitude of V from V0, is DO or greater, the pinch determinationsection 20 determines that pinching has occurred, and outputs a pulsesignal of Lo→Hi→Lo as a determination output at time t0. Upon receipt ofthis pulse signal, the control means 25 stops application of the voltageof +Vd to the drive means 24, causes the display section 26 to displayan indication of occurrence of pinching, and applies a voltage of −Vdfor a predetermined period of time to thus drive the trunk lid 1 in anopening direction, thereby releasing the pinching. There may be employedsuch a configuration that the display section 26 raises an alarm when adetermination as to occurrence of pinching is made. When pinching isreleased, the piezoelectric sensor 8 outputs a signal (a signalcomponent smaller than the reference voltage V0 of FIG. 6) in accordancewith an acceleration of recovery from deformation.

Meanwhile, in the event of occurrence of pinching, whether V becomesgreater than V0 or smaller than V0 changes according to a bendingdirection of the piezoelectric sensor 8, a polarization direction of thesame, allocation of the electrodes (as to which one of the electrodes istaken as the reference voltage), and a supporting direction of thepiezoelectric sensor 8. Therefore, there may be employed a configurationsuch that the pinch determination section 20 determines occurrence ofpinching on the basis of |V−V0|, which is an amplitude of V from V0,thereby enabling making of a determination as to occurrence of pinchingregardless of whether or not V is greater than V0.

Meanwhile, since the elastic body 8 has the cushioning section 15 whichcan be compressed under pressure applied from a pinched object, when theobject Q is pinched, the cushioning section 15 is compressed after thedetermination section 16 detects pinching until the trunk lid 1 isreversely activated; accordingly, the cushioning section 15 suppressesan increase in the pinching load applied on the object Q, therebyreducing stress or damage applied to the pinched object Q. In addition,since the cushioning section 15 is collapsed, the degree of deformationof the piezoelectric sensor 8 is increased, and the output signal fromthe piezoelectric sensor 9 is increased, detection of pinching isfacilitated.

Next, a procedure for determining occurrence of disconnection by meansof the anomalous condition determination section 21 will be describedhereinbelow. In FIG. 5, the resistance value of the sensor-side resistor27, that of the circuit-side resistor 17, and that of the signallead-through resistor 18 are respectively assumed to be R1, R2, and R3;a voltage at a point P is assumed to be Vp; and a voltage of a powersource 23 is assumed to be Vs. Resistance values of several to tens ofmegohms are usually employed as R1, R2, and R3. When the electrode ofthe piezoelectric sensor 8 is normal, Vp assumes the value of a dividedvoltage determined by R1 and the resistance values of R2 and R3 inparallel, with respect to Vs. Since the resistance value of thecomposite piezoelectric layer 10 is usually hundreds of megohms orlarger, the resistance value contributes little to the resistance valuesof R2 and R3 in parallel and, hence, is neglected in calculation of thedivided voltage value. When the electrode of the piezoelectric sensor 8is broken, the point Pa or Pb is equivalently opened, and hence Vpassumes the divided voltage value determined by R2 and R3. When a shortcircuit has arisen in the electrode, the points Pa and Pb areequivalently short-circuited, and therefore Vp becomes equal to Vs. Asdescribed above, since the anomalous condition determination section 21detects an anomalous condition, such as disconnection or a shortcircuit, of the electrodes of the piezoelectric sensor 8 on the basis ofthe value of Vp, enhanced reliability can be achieved.

Since a pressure sensor is disposed along the periphery of a trunk lidof a vehicle, pinching by the trunk lid can be directly detected by thepressure sensor through the above-described operations.

In addition, in a case where a pressure sensor includes a flexiblepiezoelectric sensor, and a contact-type pressure switch constituted ofa plurality of opposing electrodes is employed as the pressure sensorand disposed on the trunk lid, when the trunk lid includes a bentsection, the electrodes are brought into contact with each other at thebent section to thus cause erroneous detection; however, since apiezoelectric sensor has no contact, even when the piezoelectric sensoris disposed on a bent section, pinching can be detected withoutinvolvement of erroneous detection, whereby enhanced reliability can beachieved while the degree of freedom in design of the trunk lid isimproved.

In addition, the pressure sensor has the cushioning section which can becompressed by the pressure exerted by a pinched object. Even whenoccurrence of pinching is detected, the cushioning section is compresseduntil the trunk lid is reversely moved, an increase in the pinching loadexerted on the object can be suppressed, whereby stress or damageinflicted on the pinched object Q can be reduced.

Furthermore, a pinching detection apparatus employing a pressure sensorand drive means for driving the trunk lid are provided, and controlmeans which controls the drive means so as to release pinching whenoccurrence of pinching is determined on the basis of an output signalfrom the determination means is also provided. Accordingly, anopening/closing apparatus for preventing undesired pinching can beprovided.

Meanwhile, the piezoelectric sensor 8 of the present invention has thecomposite piezoelectric layer 10 constituted of a mixed compositioncontaining chlorinated polyethylene and piezoelectric ceramic powder;and the composite piezoelectric layer 10, having both advantages offlexibility pertaining to chlorinated polyethylene and high thermalstability pertaining to the piezoelectric ceramic, can operate for 1,000hours or longer at 120° C. In addition, the piezoelectric sensor 8 ofthe present invention obviates a necessity for vulcanization processing,which is required for manufacturing general synthetic rubber.

Second Embodiment

An invention of a second embodiment will be described by reference toFIGS. 7(a) and 7(b). FIGS. 7(a) and 7(b) show cross-sectional views ofthe pressure sensor 2 of a pinching detection apparatus and theinvention of the second embodiment; where FIG. 7(a) shows a state wherea predetermined load is not applied on the pressure sensor 2, and FIG.7(b) shows a state where a load of predetermined value or greater isapplied, thereby compressing the pressure sensor 2.

The second embodiment differs from the first embodiment in that thepressure sensor 2 includes a nonlinear flexible member 8 whosedeflection in relation to a load is nonlinear, and in that thepiezoelectric sensor 8 is disposed adjacent to the nonlinear flexiblemember 28. As the nonlinear flexible member 28, there is used, forinstance, a strip thin steel or reinforced resin of a convex shape asemployed in a convex gage. Such a member has a characteristic of beingabruptly deformed concavely when pressing load is increased to apredetermined value or greater and recovering to its original shape whenapplication of the load is stopped. Meanwhile, in FIG. 7(a) and 7(b),reference numeral 29 denotes a support member for supporting thenonlinear flexible member 28; 30 denotes a cushioning section; and 31denotes an elastic member of the same material as that of the firstembodiment.

In the configuration of the first embodiment, since, when a load isapplied slowly to the pressure sensor 2, the piezoelectric sensor 8deforms slowly, the signal output from the piezoelectric sensor 8becomes small, thereby, in some cases, causing a failure in pinchdetermination.

In contrast, in the second embodiment, according to the aboveconfiguration, when an object is pinched, e.g., during a period in whicha closing speed of the trunk lid 1 is slow, an upper section of thecushioning section 30 shown in FIG. 7(a) is first collapsed, whereuponthe nonlinear flexible member 28 starts being subjected to load. Whenthe load applied to the nonlinear flexible member 28 has been increasedto a predetermined value or greater by the pressure on the pressuresensor 2 by the pinched object, the nonlinear flexible member 28 of thearea having undergone pressure abruptly deforms from convex to concaveas shown in FIG. 7(b), whereby the piezoelectric sensor adjacentlydisposed thereto is also simultaneously deflected and abruptly deformed,to thus output a large output signal. As a result, the determinationmeans can determine occurrence of pinching, thereby achievingfurther-enhanced reliability of pinching detection.

Third Embodiment

An invention of a third embodiment will be described hereunder. Adifference between the third embodiment and the first and secondembodiments lies in that the object maintains contact with the pressuresensor 2 in accordance with a signal output from the piezoelectricsensor 8.

The operation stemming from the above-described configuration isdescribed by reference to FIG. 8. FIG. 8 is a characteristic viewshowing a signal V output from a filter section 19 in determinationmeans 16 of the third embodiment and a determination J output from apinch determination section 20 of the same. In FIG. 6, V and J denote,in this order, vertical axes, and a horizontal axis represents a time“t.” The filter section 19 employs a configuration analogous to those ofthe first and second embodiments.

As shown in FIG. 8, when a portion of the pressure sensor 2 of the trunklid 1 is gripped or released by a hand, a signal component greater thana reference potential V0 and a signal component smaller than the sameappear in the voltage V at a moment (time t4) when the portion isgripped and another moment (time t5) when the gripped portion isreleased. When the piezoelectric sensor 8 has already become deformedwhile remaining in a gripped state (time t4 to time 5), no signalappears. Consequently, in the case of the procedures for determiningoccurrence of pinching according to the first embodiment, when the trunklid 1 is closed while a portion of the pressure sensor 2 is gripped by ahand, the hand may still remain pinched even when pinching has arisen,so long as the piezoelectric sensor 8 has already been deformed.

As shown in FIG. 8, in the third embodiment, when V has come to V1 ormore at time t4, the pinch determination section 20 brings J to a Hilevel on the assumption that the object maintains contact with thepressure sensor until V comes to V2 or less. When V has dropped to V2 orless, the pinch determination section brings J to a Lo level on theassumption that the object is released from contact with the pressuresensor. When J is at the Hi level, the control means 25 prohibitsclosing action of the drive means 24 and provides the display section 26with a display indicating that the object maintains contact with thepressure sensor 2.

By means of the above-described operation, the determination meansdetermines whether or not the object maintains contact with the pressuresensor in accordance with the signal output from the piezoelectricsensor. For instance, when the object is determined to maintain contactwith the pressure sensor, control for prohibiting closing of the trunklid becomes possible, whereby enhanced reliability is attained.

Fourth Embodiment

An opening/closing apparatus according to an invention of a fourthembodiment will be described hereunder. In the fourth embodiment, theapparatus has a configuration for controlling the drive means 24 suchthat the trunk lid 1 is closed after having been moved over apredetermined distance in an opening direction by the control means 25.Specific procedures will be described by reference to FIG. 9. FIG. 9 isa characteristic view showing a voltage Vm applied to the drive means24. In the drawing, the vertical axis is denoted by Vm, and thehorizontal axis is denoted by time “t.” In FIG. 9, when a close switchfor commanding closing action is activated at time t6 at the time ofclosing of the trunk lid 1, the trunk lid 1 is moved in an openingdirection while the voltage applied to the drive means 24 is held at −Vduntil time t7. After time t7, Vm is held at +Vd until time t8, therebyclosing the trunk lid 1. The essential requirement is to optimizesetting of the time from time t6 to time t7 in view of the weight of thetrunk lid 1, the capability of the drive means 24, or the like. However,the time may be on the order of a minimum of hundreds milliseconds.

In the first embodiment, when the object has contacted the pressuresensor 2 before starting of closing action of the trunk lid 1, there mayarise a case where the piezoelectric sensor 8 is not subjected tosufficient deformation even after the trunk lid 1 has started closingaction, which in turn results in a failure to determine occurrence ofpinching. However, according to the above-described configuration, thetrunk lid 1 is closed after having once been moved over a predetermineddistance in the opening direction. The inertial force of the objecthaving moved in the opening direction is applied to the pressure sensor2 by means of the closing action, which in turn adds to the pressureexerted on the pressure sensor 2. As a result, the piezoelectric sensor8 is subjected to sufficient deformation, so that occurrence of pinchcan be detected without fail.

When the trunk lid 1 is closed from a fully-opened state by means of theconfiguration, there may also be employed a configuration for stoppingclosing operation after the closing operation has been [performed for agiven period of time and closing the trunk lid 1 after the trunk lid hasonce moved over a predetermined distance in the opening direction.

INDUSTRIAL APPLICABILITY

As is evident from the above-described embodiments, the presentinvention yields an advantage of the ability to detect pinching by atrunk lid, because the pressure sensor is disposed in a flexible manneralong the geometry of the trunk lid. The pressure sensor has a flexiblepiezoelectric sensor, and the sensor is not a contact-type pressuresensitive switch but a non-contact-type sensor. Therefore, even when thesensor is disposed along a bent section, there is yielded an advantageof the ability to detect occurrence of pinching without involvement ofoccurrence of a detection error and achieve improved reliability.

The pressure sensor has a nonlinear flexible member whose displacementin response to load is nonlinear. The piezoelectric sensor is disposedadjacent to the nonlinear flexible member. For instance, even when anobject is pinched when the closing speed of the trunk lid is slow, thenonlinear flexible member is quickly deformed as a result of thepressing load exerted on the pressure sensor by the object havingreached a predetermined value or more, and the adjacently-disposedpiezoelectric sensors also undergo sudden deformation, therebyoutputting a large output signal. As a result, occurrence of pinchingcan be determined by the determination means, and reliability concerningdetection of pinching is greatly enhanced.

The determination means determines whether or not the object maintainscontact with the object, on the basis of the signal output from thepiezoelectric sensor. For instance, when the object is determined tomaintain contact with the piezoelectric sensor, control for inhibitingclosing of the trunk lid becomes feasible, resulting in enhancedreliability.

The pressure sensor has a cushioning section which can be compressed bypressing action stemming from the pinched object. Even when occurrenceof pinching has been detected, the cushioning section is compresseduntil movement of the trunk lid is reversely moved. Therefore, there isan advantage of the ability to suppress an increase in pinching loadapplied to the object, thereby diminishing stress or damage inflicted onthe pinched object.

Moreover, the present invention further comprises the above-describedpinching detection apparatus, drive means for driving the trunk lid, andcontrol means for controlling the drive means so as to release pinchingwhen pinching is determined to have arisen on the basis of the signaloutput from the determination means. There is an advantage of theability to prevent occurrence of unwanted pinching, because pinching isreleased when pinching is determined to have arisen.

When the trunk lid is closed, the drive means is controlled to close thetrunk lid after the trunk lid has once been moved over a predetermineddistance in an opening direction. Even when the object has come intocontact with the piezoelectric sensor before the trunk lid startsclosing, the trunk lid is closed after having once been moved over apredetermined distance in an opening direction, so that the inertialforce of the object having moved in the opening direction is applied tothe piezoelectric sensor by means of the closing action. As a result,the piezoelectric sensor is reliably pressed, and, therefore, there isan advantage of the ability to reliably detect occurrence of pinching.

1. A pinching detection apparatus comprising: a pressure sensor disposedalong an outer edge of a trunk lid of a vehicle; and determination meansfor detecting that an object is pinched between a body opening sectionof said vehicle and said trunk lid in accordance with a signal outputfrom said pressure sensor.
 2. The pinching detection apparatus accordingto claim 1, wherein said pressure sensor has a flexible piezoelectricsensor.
 3. The pinching detection apparatus according to claim 2,wherein said pressure sensor has a nonlinear flexible member whosedisplacement in response to load is nonlinear, and said piezoelectricsensor is disposed adjacent to said nonlinear flexible member.
 4. Thepinching detection apparatus according to claim 2, wherein saiddetermination means determines whether or not said object maintainscontact with the object, on the basis of said signal output from saidpiezoelectric sensor.
 5. The pinching detection apparatus according toclaim 1, wherein said pressure sensor has a cushioning section which canbe compressed by pressing action stemming from pinching of said pinchedobject.
 6. An opening/closing apparatus comprising: a pinching detectionapparatus having a pressure sensor laid along an outer edge of a trunklid of a vehicle, and determination means for detecting that an objectis pinched between a body opening section of said vehicle and said trunklid in accordance with a signal output from said pressure sensor; drivemeans for driving said trunk lid; and control means for controlling saiddrive means so as to release pinching when occurrence of pinching hasbeen determined by said pinch determination means on the basis of asignal output from said determination means.
 7. The opening/closingapparatus according to claim 6, wherein, when closing said trunk lid,said control means controls said drive means so as to close said trunklid after said trunk lid has once been moved over a predetermineddistance in an opening direction.